92            THEOSOPHY EXPLAINED
shadow as it were. Because of this it is sometimes called
Chhaya Sharira (shadow body).  It is also sometimes
spoken of as the wraith, the fluidic body or simply the
double. It is faintly luminous and violet-grey in colour,
interpenetrating the physical body and extending about
one-fourth of an inch beyond its periphery. Its four
ethers may mingle in finer or coarser combinations like
the constituents of its denser counterpart; but the dense
body and its double vary together in quality, so that if a
man refines and purifies his physical body by pure food
and drink, the etheric double becomes purified without
any further effort.
This invisible part of the physical body is the
vehicle through which flow the streams of Prana or vital-
ity which keep the body alive, and without it, as a bridge
to convey undulations of thought and feeling from the
astral to the visible denser physical matter, the ego could
make no use of the cells of the brain.
On the shape and build of the etheric double
depend the shape and build of the physical body, so it is
the mould of the latter body.  All alterations in the
physical body from youth to old age first occur in the
etheric double before they pass on to the physical body,
and if an etheric double be defective and of a certain
shape with fine or coarse ethers for its constituents, the
physical body will be built on that etheric mould, with
similar defects and shape and composed of similarly fine,
or coarse, dense particles.
The observations of the N-rays, made by M. Jean
Becquerel in the course of his study and communicated by
him to the Paris Academy of Sciences early in the present
century, show that animals under chloroform cease to
emit N-rays, that these rays are never emitted by a